The title compound, C(4)H(8)N(3)O(+)·ClO(4) (-), is built up from creatininium cations and perchlorate anions. Crystal cohesion and perchlorate stability are ensured by N-H⋯O hydrogen bonds that together with weak C-H⋯O inter-actions build up a three-dimensional network.

The title organic salt, C(4)H(6)N(3)O(+)·C(4)H(3)O(4) (-)·C(4)H(5)N(3)O, was synthesized from cytosine base and maleic acid. An intra-molecular O-H⋯O hydrogen bond occurs in the hydrogen maleate anion. The crystal packing is stabilized by inter-molecular N-H⋯O, N-H⋯N and C-H⋯O hydrogen bonds, giving rise to a nearly planar two-dimensional network parallel to (101).

The asymmetric unit of the title compound, C(6)H(8)N(+)·HSO(4) (-), contains two cations and two anions which are linked to each other through N-H⋯O hydrogen bonds, formed by all H atoms covalently bonded to the N atoms. In addition, strong O-H⋯O anion-anion hydrogen-bond inter-actions are also observed.